Wanson Mouth exposes folded Crackington Formation sandstone and shale with a documented Langsettian ammonoid fauna. Its small beach and rocky margins are distinct from Widemouth Bay: access needs care, and public walking rights do not themselves give permission to remove fossils.
FIND FREQUENCY: ♦♦♦ – Goniatites and other small fossils have been reported, with variable preservation and exposure.
CHILDREN: ♦ – Steep bedding, slippery rocks and a tide-dependent retreat make the fossil shore unsuitable for young children.
ACCESS: ♦♦ – Use the established public-footpath approach and current signs; parking is very limited and the eroding riverside track is not the preferred route.
TYPE: Small beach, cliffs and rocky foreshore at the mouth of Wanson Water.
DIRECTIONS
♦ Follow the coastal road south through Widemouth Bay. Near the southern holiday-park area, continue onto the minor coastal road towards Millook and down the small valley. Use the established public-footpath approach from the minor road, following current signs to Wanson beach.
♦ The official coastal-access examination identified the existing public footpath as the safer approach, separate from the private, eroding track beside the river. Do not treat an old description of the riverside track as a maintained route.
♦ Parking along the narrow road is very limited. Use only lawful space, follow local notices and never obstruct entrances, verges used for passing or emergency access. The original guide’s unrestricted roadside-parking wording is not current permission.
♦ Original locality reference: 50.78031°N, 4.56078°W. This locates the locality rather than a guaranteed parking place. Check the entire shore return route before examining rocks north or south of the stream.
FOSSIL HUNTING
The best independently documented fossils are goniatites, early coiled ammonoids, with Gastrioceras cf. coronatum, Gastrioceras cf. listeri and the bivalve Dunbarella sp. recorded at several points near Wanson. The qualifiers matter: compressed or weathered fragments may not retain enough detail for a species identification. A recognisable coil, chamber divisions or consistent ornament is stronger evidence than a vaguely rounded stain.
The original guide describes black mudstone north of the stream, roughly 150–200 m along the shore at the historical reference SS1956 0127, with goniatite impressions and some more solid specimens. Sand-filled examples and buff ironstone-associated material were also reported. This is an older field record, not a guarantee of current exposure or a direction to work beneath a cliff. Examine naturally weathered surfaces of safe, permitted loose material and record the matrix before deciding that two differently preserved fossils came from the same bed.
The southern side has a separate set of original observations: small molluscs, ostracod-like remains and tube-like structures in pale gritty sandstone, and goniatite fragments near sandstone bases. The old guide places some fragments around 65–150 m south of the stream and others in foreshore outcrops approximately 200 m south. No exact-site species-level identification of the tiny carapaces or tubes is established, and sole marks or other sedimentary structures can resemble animal traces.
Dunbarella is a bivalve, so an outline or ribbed valve should not be labelled a small goniatite. Shale compression and cleavage may distort shells, while calcite replacement can erase their diagnostic detail. Higher ammonoids reported near Wanson were so recrystallised that they could not be identified confidently; their resemblance to Sandy Mouth material is not proof of a named Sandy Mouth band here.
Use a hand lens, oblique light and photographs with a scale. Keep any legally collected part and counterpart together, retain matrix and record whether the specimen was loose or in place. Photograph important in-situ finds without cutting them out. The foreshore’s scientific value includes the positions of its fossil horizons, so extraction from beds and excavation are inappropriate.
A chronological record of fossil discoveries, geological research and site history at Wanson Mouth.
1967 – Fault-separated foreshores mapped
King documented the relationship between the Wanson and Black Rock rocks, providing a framework for subsequent structural studies.
1972 – Fossil and structural evidence described
The geological memoir of the Tintagel–Bude coast recorded evidence later used to correlate the local ammonoid-bearing horizons. The year refers to publication, not a verified first find.
1990 – Coastal protected site re-notified
Boscastle to Widemouth was re-notified on 21 September, recognising geological interests along this coast.
1996 – Langsettian fossil correlation synthesised
Cleal and Thomas brought together the Gastrioceras and Dunbarella evidence and distinguished it from the unidentifiable ammonoids at a higher level.
2013 – Local 11 m sedimentary log published
Harper documented the lower ripple-rich and upper more planar-laminated intervals at Wanson, alongside their structural separation from Black Rock.
2021–2025 – Coastal access examined and opened
The formal access examination distinguished the existing public footpath from the eroding riverside track. The relevant coastal-access stretch subsequently opened on 30 January 2025; walking access remains separate from fossil-removal permission.
GEOLOGY
Wanson exposes the upper Crackington Formation of the Holsworthy Group. Pulses of sediment-laden flow supplied fine sand and silt to a marine basin, alternating with quieter mud deposition. The documented ammonoids and Dunbarella provide Langsettian age evidence for local fossil-bearing horizons, more useful than applying the whole formation’s regional age range to each exposed bed.
The sandstones, siltstones and shales were subsequently folded to steep, locally overturned attitudes and cut by faults. Thin beds can also end laterally for sedimentary reasons. Near the northern boundary, the Widemouth South Fault separates these rocks from the lower Bude Formation at Black Rock. A walk from Wanson towards Widemouth therefore crosses a structural interruption rather than a complete conformable formation transition.
A measured 11 m section at Wanson records a change from ripple-laminated beds with occasional trough cross-lamination below to a more planar-laminated, muddier upper part. It is a small local window, not the entire Crackington Formation. Secondary quartz veins and deformation cut the sedimentary structures, and neither should be mistaken for a fossil band. The detailed account below keeps the measured section separate from the marine-band correlations.
Detailed geology and stratigraphy of Wanson Mouth, including the limits of local correlation.
The account covers Wanson Water mouth and the adjoining foreshore. The 11 m log at SS1955 0136, broader fossil occurrences and the fault boundary are separate observations. Black Rock’s numbered shale scheme is not imported here.
HOLSWORTHY GROUP
The formal parent group of the Crackington Formation.
Crackington Formation
Upper Crackington sandstone, siltstone and shale form steep to overturned beds at Wanson. The described log contains no grains coarser than fine sand. “Wanson Beds” is historical terminology; no verified formal local member is added.
Measured lower 5.5 m
Mud-draped ripple-coset lamination occurs with occasional trough cross-laminated sandstone. These structures indicate changing currents and sediment supply. The figure shows a succession of distinct facies intervals, described below without invented precise boundary measurements.
Basal ripple-coset beds
The base of the illustrated log contains mud-draped ripple-coset lamination in siltstone and sandstone. These are primary sedimentary structures, not a named fossil bed.
Lower trough cross-stratified interval
A sandstone interval above the basal ripple beds has mud-draped trough cross-stratification and later quartz veins. The veins cut the sediment and are not part of its original depositional layering.
Return to ripple-coset bedding
Higher in the lower half, ripple-coset siltstone and sandstone alternate, including a veined interbedded package. Keep this repetition of facies distinct from any demonstrated tectonic repetition.
Second trough cross-stratified interval
The illustrated lower half contains another mud-draped trough cross-stratified interval. The log notes quartz veins and an early normal fault at its base; these secondary structures must not be labelled fossil traces.
Planar shale grading into ripple-coset siltstone
Above that interval, planar-laminated shale passes into ripple-coset siltstone, followed by further mud-draped ripple beds with local quartz veins. The log records sedimentary transitions rather than a series of formal beds.
Measured upper 5.5 m
The upper half lacks the trough cross-laminated sandstones of the lower half and contains fewer ripple-laminated beds. Planar-laminated siltstone and shale dominate, interpreted as relatively lower-energy deposition.
Lenticular and planar-laminated upper beds
The figure distinguishes interbedded mud-draped ripple-coset and lenticular planar-laminated siltstone and sandstone, associated with planar shale. Above are repeated transitions between ripple and planar lamination, locally crossed by quartz veins.
Upper ripple beds and vein-crossed interval
A further ripple-coset siltstone–sandstone package occurs below the cap, with quartz veins cutting some ripple sets. Ripple structures do not disappear entirely from the upper half even though they become less prominent.
Planar-laminated shale cap, 0.75 m
The top of the published figure explicitly labels a thick, 0.75 m planar-laminated shale. The author suggests that it may indicate sediment cut-off. This is a scoped measurement of the local cap, not a named marine-band thickness or the top of the formation.
Broader foreshore bedding and sole marks
Thin sandstone and siltstone beds can pinch out laterally. Bed bases preserve abundant sole structures related to sediment movement. A groove or flute mould is not automatically a worm trace. The measured log cannot be extrapolated unchanged across the folded foreshore.
Langsettian fossil-bearing horizons
The documented Gastrioceras cf. coronatum, Gastrioceras cf. listeri and Dunbarella sp. assemblage supports correlation with the Gull Rock Shale near Clovelly and the Listeri Marine Band. This is biostratigraphic correlation, not evidence that the full Clovelly log is exposed here.
Higher recrystallised ammonoids
A higher occurrence near Wanson contains ammonoids thoroughly replaced by calcite and not identifiable. A comparison with Sandy Mouth material was suggested, but a secure local Sandy Mouth Shale correlation was not established.
Museum specimens and identification limits
The collection includes Wanson specimens historically identified as Gastrioceras coronatum and a Gastrioceras listeri-group specimen, GSM103153. They support locality records, not present abundance or new type status. Conflicting age metadata on another catalogue record must not override the local stratigraphic evidence.
Widemouth South Fault
This fault separates the Wanson and Black Rock successions. Proposed histories differ, including thrust-related structures and later extension. Do not portray the contact as an uninterrupted stratigraphic passage or give a regional separation estimate as measured local displacement.
References
Harper (2013), Assessing the mechanical state of sediment and rock during deformation, University of Leeds thesis, Chapter 4, Figs 4.12–4.15
Cleal & Thomas (1996), British Upper Carboniferous Stratigraphy, GCR 11, Chapter 3: Culm Trough, especially the Crackington Coast account
BGS Lexicon: Holsworthy Group
BGS Lexicon: Crackington Formation
BGS Palaeosaurus: Wanson Mouth specimen GSM103127; geological metadata inconsistent
BGS Palaeosaurus: Wanson Mouth, Gastrioceras listeri-group specimen GSM103153
Craven & Lloyd (2023), Reconciling onshore and offshore geological mapping: lessons from north Cornwall, SW England, Geological Society Special Publications 541
SAFETY
The rocky margins and headlands can be cut off. Visit only with suitable tide and swell conditions, a clear exit and a conservative return margin. The former suggestion that collecting is possible at any time is unsafe: neither a visible beach nor an incoming tide guarantees a usable retreat.
Steep bedding, slippery surfaces, loose blocks, rockfall and eroding paths are the principal hazards. Avoid cliff bases and do not force a route across unstable ground. Widemouth’s lifeguard service should not be assumed to cover this small beach.
EQUIPMENT
Carry a hand lens, camera, tide/weather information, water and suitable grip-soled footwear. Wrapping and a rigid box can protect small loose specimens where removal is permitted. Leave excavation tools behind and avoid using the cliffs or steep slabs as work surfaces.
CLEANING AND TREATING
Keep mudstone flat and supported, allow it to dry gradually and begin with gentle dry brushing. Retain counterparts and matrix. Do not use acid on calcite-replaced ammonoids: the mineral you dissolve may be the fossil. Avoid bleach, varnish and aggressive preparation, especially before a potentially significant specimen has been assessed.
IDENTIFY YOUR FINDS
Need help identifying a fossil? Share clear photos, where you found it and its size with the community.
FURTHER READING
Cleal & Thomas (1996), British Upper Carboniferous Stratigraphy, GCR 11, Chapter 3: Culm Trough, especially the Crackington Coast account
BGS Lexicon: Crackington Formation
Harper (2013), Assessing the mechanical state of sediment and rock during deformation, University of Leeds thesis, Chapter 4, Figs 4.12–4.15
BGS Palaeosaurus: Wanson Mouth, Gastrioceras listeri-group specimen GSM103153
Alison Lea (2021), coastal-access inspector’s report, Wanson Mouth, MCA/MNQ2/0/2
Natural England: Marsland Mouth to Newquay coastal-access approval and opening
ACCESS RIGHTS
Wanson lies within Boscastle to Widemouth SSSI. An established public footpath reaches the beach, and the relevant coastal-access stretch opened in January 2025. Use current signs and observe any local restriction; private ownership alone is not proof that the whole beach is closed.
Public walking access does not authorise fossil removal. Observe and photograph the beds, and take loose material only where the current landowner’s policy allows it. Do not hammer cliffs or bedrock, clear boulders or excavate profiles. The original unrestricted-collecting claim must not be relied on.
Original guide’s designation document (historical copy; check current notices and the official site record above): SSSI Information – Wanson Mouth
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